Preheat oven to 375F.,Pierce potato with fork.,Place potato on oven rack and bake until very soft, about 1 hour.,Remove from oven and cool.,______,Arrange eggplant rounds on prepared sheets.,Bake eggplant 15 minutes.,Cover with foil.,Bake until very soft and brown, about 30 minutes longer.,Heat 1/4 cup olive oil in heavy large saucepan over medium-high heat.,Add onion, garlic and oregano and saute until onion and garlic are translucent, about 10 minutes.,Cut potato into pieces.,Combine potato, eggplant and onion mixture in processor.,With machine running, gradually add chicken stock and blend until smooth.,Transfer to saucepan.,Add saffron and bring to simmer.,Serve hot.,(Can be prepared 1 day ahead.,Cover and refrigerate.,Reheat before serving.)